Here is a real life example of using morse code by beating on a sunken
submarine hull -- The USS Squalus in 1939

"Two ships arrived on the scene during the afternoon. Their propellers could
be heard clearly in the Squalus. One had an oscillator for generating
underwater sound, making possible Morse code transmissions. The Squalus
responded by laboriously beating out answers by hammering on the hull. One
blow was a dot and two a dash."

URL:
http://www.onr.navy.mil/focus/blowba...s/sinking3.htm


--
CL -- I doubt, therefore I might be !






"Wayne Jones" wrote in message
.. .
I have used morse code with a key (ve3gqx) but have always wondered how
people sent and recieved code by tapping on pipes etc.
Can anyone explain how this is done? How does one distinguish between a
dot and a dash?

tnx
Wayne